Field of the Invention
The present invention is broadly concerned with very small and compact magnetic switch assemblies, which can be mounted on conventional circuit boards. More particularly, the invention is concerned with such switch assemblies having low-profile switch housings with internal electrodes and shiftable components within the housings that are shiftable between separate switch-operating positions depending upon the magnetic field conditions imposed upon the components. The switch assemblies may be used, e.g., as a part of window or door monitoring/alarm systems, or as proximity sensors.
Description of the Prior Art
Prior art alarm systems use magnetic switches attached to doors and/or windows for detecting unauthorized opening thereof. One common type of magnetic switch is a so-called reed switch. This type of switch is subject to unauthorized manipulation through use of an external magnet. That is, an intruder can use a strong magnet held in proximity to the reed switch to hold the switch closed (or open depending upon the control scheme), and thereby open a supposedly protected door or window without triggering the alarm system.
Magnasphere Corporation of Waukesha, Wis. commercializes a specialized type of magnetic switch giving improved performance and protection against external magnet manipulation. Such switches generally comprise a metallic housing with an internal switch ball shiftable between a first position in contact with a pair of switch electrodes and a second position out of such simultaneous contact. Switches of this type are disclosed in U.S. Pat. Nos. 5,977,873 and 7,291,794. Other prior references include U.S. Pat. Nos. 5,332,992, 5,530,428, 5,673,021, 5,880,659, 6,087,936, 6,506,987, 6,603,378, 6,803,845, 7,023,308, RE39,731, 7,825,801, 7,944,334, 8,228,191, 8,314,698, 8,487,726, 8,648,720, and 8,941,397, and EP 2638555.
Although the present-day Magnasphere switches are of inherently small and compact design, they are generally too large for direct mounting on circuit boards. It would be a decided advantage if even more compact switch assemblies could be provided, which retain the unique operating properties of the existing switches, while also being mountable directly on circuit boards.